Motor-driven centrifugal pump for liquid



P 1945. G. c. MEREDEW 2,384,254

MOTOR-DRIVEN CENTRIFUGAL PUMP FOR LIQUID Filed June 17, 1943 2 Sheets-Sheet l InvonTor:

W 6. WW '8 (4 l6 q I hriwnaqs l .1945- Y G. c. MEREDEW 2,384,254

MOTOR-DRIVEN CENTRIFUGAL PUMP FOR LIQUID Filed June 17-, 1943 2 Sheets-Sheet 2 Die/Iz L JM a4 Ma /(A12 Patented Sept. 4, 1945 MOTOR-DRIVEN CENTRIFUGAL PUMP run George Charles Mei-ode signer to Sell? co. Limited, rune w, lilondon, England, as- Pump 8; Engineering England, a British com- Appiication June 17, 1943, Serial No. 491,183 in Great Britain April 20, 19%2 2 Claims.

This invention relates to motor-driven centrifugal pumps for pumping liquids and of the type in which the driving motor, usually an electric motor, the motor housing and the pump impeller, usually direct-coupled to the motor haft, are arranged to form a unit removably mounted in a base (hereinafter referred to as the base casting) which provides inlet and outlet flow conduits for the liquid, and a trunk-like portion tfor the reception of the motor-impeller unit.

This invention is particularly, although not exclusively, concerned with the pressure feeding, by means of pumps of the above type, of petrol 01' other liquid fuel to internal-combustion engines, especially aircraft engines. In such cases the inlet conduit or the base casting is coupled directly to, or otherwise put in communication with, the lower end of the petrol storage tank and the outlet conduit is arranged to deliver to the carburettor system of the engine.

Whether the pump is employed for the above purpose or for other applications, the petrol or other liquid to be pumped will normally be supplied under a head to the inlet conduit of the base casting and, unles provision were made to prevent it, the liquid would escape through the base casting on withdrawal of the removable motorimpeller unit, e. g. for inspection, repair or for the purpose of interchanging units.

This invention provides, in a motor-driven centrifugal pump of the type described, a valve or equivalent device associated with the base casting to control the inlet conduit thereof, and movable by or through the intermediary oi the motor-impeller unit during its insertion in, or withdrawal from, the base casting 1n such manner that on withdrawal or insertion of the unit the valve will be automatically closed or opened respectively.

In one arrangement according to the invention the sealing means comprises a valve mounted in the base casting and guided for movement in alignment with the motor-impeller unit, spring means tending to move the valve in the direction of withdrawal of the motor, unit and against a seating to close the inlet conduit 01 the base casing against entry of liquid, and an abutment or abutments carried by the impeller end of the motor unit and located to engage the valve and move it to the open position on insertion of the unit and on withdrawal of the unit to release the valve for return movement under its control spring to th closed position.

One construction embodying the foregoing and other features of the invention will now be described by way of example with reference to the accompanying drawings, in which:

Figure 1 is a central longitudinal section of the pump;

Figure 2 is a plan of the pump, and

Figure 3 is a sketch '(partly in section) showing the disposition of the parts on withdrawal of the motor-impeller unit.

Like reference numerals indicate like parts in the three figures.

The pump is designed for the pressure feeding of petrol or other liquid fuel from a storage tank to the carburettor system of an internal-combustion engine installation for use in aircraft, or for the transference of fuel from one storage tank to another on an aircraft. The pump comprises a base casting 5 which provides an inlet conduit 5 and an outlet conduit 1 for the liquid fuel. The base casting 5 is adapted to be coupled directly to the bottom wall 8 of the storage tank and for this purpose is formed with a spigot portion 9 adapted to enter an aperture in the tank wall and with a flange I G to surround the aperture and to be bolted, through bolt holes ii, to the tank wall.

The base casting 5 is formed with an integral trunk portion l2 arranged to receive the removable motor-impeller unit. The removable unit comprises a housing l3 containing a driving motor as and an impeller I5 direct-coupled to the motor shaft l 6 which is suitably journalled in end bearings IT. The inner end of the motor shaft extends through a, liquid sealing gland l8 of any suitable type arranged to be drained through a conduit E9.

The removable motor-impeller unit in this example embodies the invention described in the specification of British patent application No. 5279/42, in that thewhole of the impeller casing, including the annular wall which defines the inlet throat of the impeller chamber, is formed as part of the removable unit. The impeller chamber is formed in a block 20 which is secured by bolts 2| to the impeller end of the motor housing. The annular inlet wall of the impeller chamber which defines the inlet throat is formed as a. removable insert 22 screwthreaded into the block 20. With this arrangement the insert 22 may be accurately adjusted, by rotation relative to the block 20, to give the desired throat clearance.

The block 20 is formed with a barrel extension 23 adapted to nest within the trunk-like portion l2 of the base casting, the outer end of the extension 23 being formed with a flange 24 to engage over the corresponding end of the base casting trunk. The removable unit is held in place- 'ouring nut 25 is turned in a direction to release the motor unit, the bezel ring 28 will bear on the projecting rib 21 of the motor housing and will force the motor unit outwardly from the base casting.- It will also be understood that with this arrangement the securing nut 25 with its bezel ring forms part of the removable motor unit.

The self-sealing means for the inlet conduit 6 oi the base casting comprises a mushroom valve 28 accommodated in a housing 29 which forms part of the spigot portion 9 of the base casting. The valve 28 is positioned in alignment with the central axis of the motor-impeller unit and is guided for rectilinear movement in the direction of the longitudinal axis of the motor unit by a' guiding sleeve 30 forming part of the housing 29. The housing 29 also provides a illter 31. The valve-28 is arranged to co-operate with a seating 32 in the base casting and it is under the control of a compression spring 33 which tends to force the valve towards the seating 32, i. e. towards the closed position in which the inlet conduit 8 is sealed against the entry of liquid from the storage tank. The bolts H which secure the impeller casing block 20 to the motor housing are formed with extensions 34 adapted to act as abutments for co-operation with the valve 28. The abutments 34 are so located as to eng e the valve 28 and move it to the open position (against th action of the spring 33) on insertion of the motor unit, and on withdrawal of the unit gradually to release the valve for return movement under its control spring to the closed position, shown in Figure 3.

The motor unit is sealed in the assembled posltion by means of packing rings inset in the barrel extension 23 oi the impeller casing block. The rings 35 are so positioned in relation to the travel of the valve 28, i. e. in relation to the eftective projection of the abutment: 34 so as to ensure that, on removal or the motor unit, an efiective seal between it and the trunk portion l2 of the base casting will not be broken until the mushroom valve is properly seated in the closed Which.

The base casting also embodies a by-pass 36 between the inlet and outlet conduits 8, 1, controlled by a suction valve 31 so arranged that in the event of a failure of the motor-impeller unit or in any circumstances in which that unit ma noperative, the induction pull of the engine ing the resistance which would thereby be imposed when the impeller is stationary.

It is to be understood that while normally an electric motor will be used as the driving means in the motor-impeller unit, the invention may equally well be embodied in pumps of the type described in which other motors, for example pneumatically driven motors are employed. It is also to be understood that the term base casting is employed. in a broad sense to 'cover the trunk-like unit which receives the motor-impeller irrespective of the position in which the unit is disposed. In the particular example described above the base casting is arranged vertically in relation to the bottom of the petrol storage tank; it may equally well be arranged horizontally or at any suitable angle between the vertical and horizontal positions. It is also to be understood that various modifications may be made in the construction described with re!- erence to the drawings without departing from the essential features of the invention. For example, a valve, other than one of the mushroom type, may be used as the self-sealing device for the inlet conduit of the base casting, and means, other than those described, may be employed for securing the removable motor-impeller unit in the trunk portion of the base casting.

I claim:

1. A motor-driven centrifugal pump for liquid comprising a base casting providing a hollow trunk portion and inlet and outlet flow conduits for the liquid, a motor impeller unit removably received in the hollow trunk portion of the base casting and including a driving motor, a housing therefor, a direct-coupled pump impeller, and an impeller chamber formed on a blocksecured by bolts to the impeller end of the motor housing, a

valve mounted in the base casting and guided for movement in alignment with the motor-impeller unit, spring means tending to move the valve in the direction of withdrawal of the motor unit and against a seating to close the inlet conduit of the base casting against entry of liquid, and an abutment formed by an extension of at least one of the bolts by which the aforesaid block is accured to the motor housing and located to engage the valve and move it to the open position on insertion of the unit, and on withdrawal of the unit to release the valve for return movement under its control spring.

2. A centrifugal pump according to claim 1 in which the aforesaid impeller-chamber block is formed with an extended annular wall which is fitted within the base casting trunk and has an out-tumed flange adapted to bear on the outer end or the trunk, combined with a nut screwthreaded to the trunk and provided with an inward-1y extending bezel ring engaging over the aforesaid flange on the extended annular wall of the impeller chamber block, and beyond the belel ring a peripheral rib on the outside of the motor housing and overlapping the inner echo of the bezel rin'g.

GEORGE CHARLES 

